I had a pretty bad dieseling problem, but I did the Sea Foam thing to get rid of carbon deposits. No more dieseling. Just unplugged the PCV and stuck the hose into the can, then let 'er rip. Smoked out the neighborhood!
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| dieseling cure https://www.slantsix.org/forum/viewtopic.php?t=40604 |
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| Author: | carlherrnstein [ Sat Jun 12, 2010 12:22 pm ] |
| Post subject: | dieseling cure |
I have a dieseling problem the engine has.. a new holley 2280, a working choke, working warm air snorkel, new autolite 26 plugs, hei, electric fan, new 195 thermostat, new cap, new rotor, new wires, no egr, base timing at 15 degrees before tdc. The idle is 550 rpm, the head was rebuilt with all new exhaust valves. It will diesel for 2-3 sec after i turn it off. Sorry for all the stats but, I'm out of ideas. Thanks for any help. |
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| Author: | wjajr [ Sat Jun 12, 2010 1:01 pm ] |
| Post subject: | |
I have a Holley 390, sitting on a reworked head, and have had dieseling or back spin problems. Because of a rather aggressive cam, and a low vacuum reading at an in gear idle of 600 rpm, the power valve was activated causing a rich condition. I had to go to a 2.5, it still acts up on occasion, and now I will be installing a 1.0 power valve. First check float level, and adjust if necessary. A high level will dump excessive fuel and can cause that back spin, or dieseling. Second if float is level is good, test your power valve to be sure it is not leaking or blown (I just put the large end to my mouth and suck on it- if no air passes it is ok), and follow Holley’s recommendation for power valve selection based on your vacuum reading at in gear idle. |
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| Author: | dennday67 [ Sat Jun 12, 2010 8:26 pm ] |
| Post subject: | |
yum power valve its whats for dinner. |
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| Author: | coconuteater64 [ Sat Jun 12, 2010 9:17 pm ] |
| Post subject: | |
I had a pretty bad dieseling problem, but I did the Sea Foam thing to get rid of carbon deposits. No more dieseling. Just unplugged the PCV and stuck the hose into the can, then let 'er rip. Smoked out the neighborhood!
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| Author: | DusterIdiot [ Sun Jun 13, 2010 12:17 pm ] |
| Post subject: | Another thing to note... |
Dieseling and "run on" can also be caused by a vacc leak at the carb, or improper seating of the throttle plates. FYI, -D.Idiot |
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| Author: | carlherrnstein [ Sun Jun 13, 2010 12:38 pm ] |
| Post subject: | |
Thanks for the ideas I will check them out and report back. |
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| Author: | ESP47 [ Mon Jun 14, 2010 9:31 pm ] |
| Post subject: | |
Your timing is pretty aggressive. I'd back it off to 8* or so and see if that helps. |
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| Author: | FrankRaso [ Tue Jun 15, 2010 6:10 am ] |
| Post subject: | Ignition Advance |
Running as much advance as possible doesn't necessary give the best fuel economy and/or power. The advance curves need to be set so that the pressure peak in the combustion chamber creates the maximum torque on the crankshaft. Too much or too little advance wastes power and fuel. However, insufficient octane will often cause pinging before reaching the point of best torque. |
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| Author: | KBB_of_TMC [ Tue Jun 15, 2010 7:46 am ] |
| Post subject: | |
I had that problem on a '75 Coronet w/ 225ci /6; I built a box w/ solenoid valves that let me connect the EGR to manifold vacuum before I turned the car off - the RPMs would way drop down and then it wouldn't run on anymore. The same box could disable EGR entirely for WOT, but let its vacuum amplifier run normally to prevent pinging at mild throttle. The box had 3 solenoid valves and a dash mounted 3 position switch for (vacuum amplifier) | (manifold vacuum) | (vent to air) to the vacuum input on the EGR valve. I couldn't measure any difference in mileage w/ EGR vented or connected to the amplifier. |
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| Author: | 1969ronnie [ Tue Jun 15, 2010 8:43 am ] |
| Post subject: | |
shut it off in gear. the trans load will stall it immediately. ron |
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| Author: | carlherrnstein [ Tue Jun 15, 2010 11:09 am ] |
| Post subject: | |
I checked the power valve adjustment ...and there is no screw I think. I will reset the base timing to 8* and see how it does thanks for the help |
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| Author: | wjajr [ Tue Jun 15, 2010 1:31 pm ] |
| Post subject: | |
carlherrnstein: Quote: I checked the power valve adjustment ...and there is no screw I think.
There is no adjustment of a power valve, it must be changed for another that meets ones idle vacuum requirements. Also they are either operational, or the diaphragm is ruptured rendering it useless. See one here.In order to service a Holley power valve one must remove the float bowl, then the block holding the jets. From the back side of the block, use a one inch wrench to gently remove the valve. Don’t over tighten the power valve when installing it, be gentle. |
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| Author: | carlherrnstein [ Tue Jun 15, 2010 2:52 pm ] |
| Post subject: | |
ok, thanks wjajr I thought the power valve was something else I'm not too keen on carburetors but I'm trying to learn. |
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| Author: | carlherrnstein [ Fri Jun 18, 2010 2:15 pm ] |
| Post subject: | |
I reset the timing to 8* and it helped a bit now it only diesel when the engine it warm... I have the plugs gaped to .045"or .050" I can't remember could that be too far? Also the carburetor gets hot to touch I wonder if the fuel is boiling making it run richer than normal and causing it to diesel. any ideas? |
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| Author: | Aggressive Ted [ Fri Jun 18, 2010 2:44 pm ] |
| Post subject: | |
Yes......running too hot with too much timing and fuel boiling can cause it to diesel especially on a stock low compression motor. As the compression is increased it helps to minimize run on. Click on the red link below my name and take a look at the heat deflector under my carb. It really helps allot.......the carb stays much cooler, never hot. Having a electric fan to cool everything down after the engine is shut off helps allot too! SL6Dan's fuel line mod is also great improvement. Restarts after heat soak is immediate! I run .045 gap on the plugs. Running hot is great for best mileage but it easy to get too hot under the hood on the hotter 100 plus degree days. |
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